package calcite;

import org.apache.calcite.DataContext;
import org.apache.calcite.adapter.java.AbstractQueryableTable;
import org.apache.calcite.adapter.java.JavaTypeFactory;
import org.apache.calcite.linq4j.Enumerable;
import org.apache.calcite.linq4j.Linq4j;
import org.apache.calcite.linq4j.QueryProvider;
import org.apache.calcite.linq4j.Queryable;
import org.apache.calcite.plan.RelOptUtil;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.rel.type.RelDataTypeFactory;
import org.apache.calcite.schema.SchemaPlus;
import org.apache.calcite.schema.Table;
import org.apache.calcite.schema.impl.AbstractSchema;
import org.apache.calcite.schema.impl.ScalarFunctionImpl;
import org.apache.calcite.sql.SqlFunctionCategory;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.parser.SqlParseException;
import org.apache.calcite.sql.parser.SqlParser;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.calcite.tools.FrameworkConfig;
import org.apache.calcite.tools.Frameworks;
import org.apache.calcite.tools.Planner;
import org.apache.calcite.tools.RelConversionException;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.*;

public class CustomMySQLExecutionEngine {
    // Custom schema representing the MySQL table
    /*
    public static class MySQLSchema extends AbstractSchema {
        @Override
        protected Map<String, Table> getTableMap() {
            Map<String, Table> tables = new HashMap<>();
            tables.put("largeTable",
                    new AbstractQueryableTable(Object[].class) {
                        @Override
                        public RelDataType getRowType(RelDataTypeFactory typeFactory) {
                            return null;
                        }

                        @Override
                        public RelDataType getRowType(JavaTypeFactory typeFactory) {
                            // Define the schema of the MySQL table
                            return typeFactory.createStructType(
                                    Arrays.asList(
                                            typeFactory.createSqlType(SqlTypeName.INTEGER),
                                            typeFactory.createSqlType(SqlTypeName.VARCHAR)
                                            // Add more columns as needed
                                    ),
                                    Arrays.asList(
                                            "id",
                                            "name"
                                            // Add column names corresponding to the schema
                                    )
                            );
                        }

                        @Override
                        public <T> Queryable<T> asQueryable(QueryProvider queryProvider, SchemaPlus schema, String tableName) {
                            return new AbstractQueryableTable.QueryableTableScan<>(queryProvider, schema, this, tableName) {
                                public Enumerable<T> enumerator() {
                                    // Implement logic to execute large table query on MySQL
                                    Connection connection = null;
                                    Statement statement = null;
                                    ResultSet resultSet = null;
                                    List<T> results = new ArrayList<>();
                                    try {
                                        connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/database", "username", "password");
                                        statement = connection.createStatement();
                                        resultSet = statement.executeQuery("SELECT * FROM largeTable");
                                        while (resultSet.next()) {
                                            // Process the result set and construct objects of type T
                                            // Add objects to the 'results' list
                                        }
                                    } catch (SQLException e) {
                                        e.printStackTrace();
                                    } finally {
                                        try {
                                            if (resultSet != null) resultSet.close();
                                            if (statement != null) statement.close();
                                            if (connection != null) connection.close();
                                        } catch (SQLException e) {
                                            e.printStackTrace();
                                        }
                                    }
                                    return Linq4j.asEnumerable(results);
                                }
                            };
                        }
                    });
            return tables;
        }
    }*/

    public static void main(String[] args) throws SqlParseException, RelConversionException {
        // Create a root schema and add the custom MySQL schema
        SchemaPlus rootSchema = Frameworks.createRootSchema(true);
       // rootSchema.add("mySQLSchema", new MySQLSchema());
        // Add custom MySQL functions if needed
        //rootSchema.add("mySQLFunctions", ScalarFunctionImpl.create(MySQLCustomFunctions.class, "MY_SQL_FUNCTION", SqlFunctionCategory.USER_DEFINED_FUNCTION));
        // Create a planner and set the root schema
        FrameworkConfig config = Frameworks.newConfigBuilder()
                .defaultSchema(rootSchema)
                .build();
        Planner planner = Frameworks.getPlanner(config);
        // Execute large table queries using the custom MySQL execution engine
        String query = "SELECT * FROM largeTable WHERE id > 1000";
        SqlParser parser = SqlParser.create(query, SqlParser.Config.DEFAULT);
        SqlNode sqlNode = parser.parseQuery(query);
        //RelNode logicalPlan = planner.rel(sqlNode);
        //RelNode physicalPlan = planner.transform(0, RelOptUtil.splitFilter(RelOptUtil.pushFilterPastProject(logicalPlan)));
        // Execute the physical plan using the custom MySQL execution engine
        // ...
    }


    public static class MySQLCustomFunctions {
        // Define custom MySQL functions
        // Example:
        public static String mySqlFunction(DataContext dataContext, int arg) {
            // Implement custom function logic
            return "Result of custom MySQL function";
        }

    }

}